How to Determine What Portable Air Conditioner Size to Get

Posted by Brenda Roy on Jun 13, 2017

how-to-determine-what-portable-air-conditioner-size-to-getIf you're shopping for a mobile spot cooler, you may be wondering what portable air conditioner size you need. Most units will be rated in BTUs — but what the heck does that mean? BTU stands for "British Thermal Unit" and it represents the amount of energy needed to increase the temperature of one pound of water by one degree Fahrenheit. 

Generally, the bigger the area you need to cool, the more BTUs you will need. 

Take our advice: Don't buy an air conditioner that's too large. An oversized portable air conditioner is actually less effective as opposed to more cooling — and can waste valuable energy at the same time. That means a negative impact on the bottom line of your business. 

Because portable air conditioners remove both heat and humidity from the air, an oversized unit may cool the room quickly, but only remove some of the humidity. This will leave your room with a damp, clammy feeling. A properly sized unit will effectively remove humidity as it cools. That means more comfort all around. 

Figure out square footage

Size matters. First determine the square footage of the room or area you need to cool. 

Determine the square footage of the area to be cooled with a portable air conditioner using the following formulas:

  • Square and rectangular rooms: Multiply the length of the area by its width — L x W
  • Triangular rooms: Multiply the length of the area by the width and divide it in half — (L x W) / 2

Determine the BTUs needed

Once you have the square footage, refer to the chart below to determine the correct cooling capacity for your portable spot cooler

Area to Be Cooled (Square Feet)  Capacity Needed (BTUs per Hour) 
100 to 150 5,000
150 to 250 6,000
250 to 300 7,000
300 to 350 8,000
350 to 400 9,000
400 to 450 10,000
450 to 550 12,000
500 to 700 14,000
700 to 1,000 18,000

Make any adjustments for the following circumstances:

  • If the room is heavily shaded, reduce capacity by 10 percent.
  • If the room is very sunny, increase capacity by 10 percent.
  • If more than two people regularly occupy the room, add 600 BTUs for each additional person.
  • If the unit is used in a kitchen, increase capacity by 4,000 BTUs.
  • Consider where you install the unit. If you are mounting an air conditioner near the corner of a room, look for a unit that can send the airflow in the right direction.

Still need advice? Talk to an indoor environmental solutions expert about any special cooling needs you have.

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Topics: Portable Air Conditioners

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